Tobacco curing and drying apparatus



June 18, 1968 .J. 5. TAYLOR TOBACCO CURING AND DRYING APPARATUS 5Sheets-Sheet 1 Filed June 7, 1966 June 18, 1968 J. S. TAYLOR TOBACCOCURING AND DRYING APPARATUS 5 Sheets-Sheet 2 Filed June '7, 1966 I AWIH7 lyJul-m 5'. Ta Zar June 18, 1968 J. 5. TAYLOR 3,388,900

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TOBACCO CURING AND DRYING APPARATUS Filed June '7, 1966 5 Sheets-Sheet 5IZ\Z\ T r W m T f 33 Ji rz g ur United States Patent 3,388,900 TOBACCOCURING AND DRYING APPARATUS John S. Taylor, Jacksonville, Fla., assignorto Tlfcon Company, Jacksonville, Fla., a corporation of Florida FiledJune 7, 1966, Ser. No. 555,796 Claims. (Cl. 263-19) ABSTRACT OF THEDISCLOSURE A tobacco curing barn with the tobacco to be cured hanging intiers, has an air heating and circulating unit setting on the middle ofthe floor of the barn. The air is drawn into the top of the unit by anair circulating fan and is discharged from the bottom thereof along withthe products of combustion to flow radially in all directions across thefloor of the barn. The air heating and circulating unit has a cup-shapedfire pot coaxial with and located in the bottom portion of an invertedcupshaped outer casing. The side walls of the fire pot and outer casingare uniformly spaced to provide an annular air passage. Legs on the unitsupport the same with the bottom edge of the casing spaced above thefloor of the barn to provide an outlet from the annular air passage. Ahood-like flame shield supported above the fire pot directs the airdrawn into the top of the unit into the annular air passage. Theperipheral portion of the flame shield projects beyond the mouth of thefire pot to constrict the entrance into the annular air passage andproduces a low pressure zone at the mouth of the fire pot. An oil burnernozzle supported on the top wall of the outer casing receives air forcombustion from the air circulating fan and directs flame down into thefire pot.

This invention relates to the tobacco curing art and has as its purposeto provide a simple, inexpensive, selfcontained portable air heating andcirculating unit adapted to be set directly on the floor of a tobaccocuring barn and to coact with the barn floor in effecting forcedcirculation of the air throughout the entire barn, with the hottest airmoving along the floor and radiating from the unit in all directionstowards the perimeter of the floor.

Another object of this invention is to provide a portable,self-contained air heating and circulating unit which, though designedand intended especially for use in curing and drying tobacco, can beused for a wide variety of other purposes.

With a view toward achieving low cost, it is a specific object of thisinvention to provide a forced air heating and circulating unit in whichthe heat source comprises a burner nozzle arranged to direct flame intoa combustion zone or fire pot, and wherein a single blower effectscirculation of the air through the unit and also supplies combustion airto the burner nozzle and the combustion zone.

Also with a view toward achieving low cost, it is another object of thisinvention to provide an air heating and circulating unit of thecharacter described wherein an oil burner having a fuel pump providesthe heat source, and a common drive motor drives the fuel pump and alsoan air circulating fan or blower by which the air is circulated throughthe unit.

In an air heating and circulating unit designed especially for use incuring and drying tobacco, it is customary to discharge the bot gasesand products of combustion from the combustion zone or chamber of theunit directly into the air stream being circulated through the unit. Toachieve good combustion under these conditions, it is essential thatonly the air needed for combustion be fed into the combustion zone, andalso that the combus- 3,3883% Patented June 18, 1968 tion zone beeffectively insulated from the air being circulated through the unit.

This invention assures the attainment of these objectives by a uniqueconcentric arrangement of the combustion chamber and the air passagethrough which the air flows as it is circulated through the unit, and anovel Way of communicating these spaces or zones; and by the pro visionof an effective flame shield to insulate the combustion zone from thecooling effect of the air being circulated through the unit.

With the above and other objects in view which will appear as thedescription proceeds, this invention resides in the novel construction,combination and arrangement of parts substantially as hereinafterdescribed and more particularly defined by the appended claims, it beingunderstood that such changes in the precise embodiment of thehereindisclosed invention may be made as come with in the scope of theclaims.

The accompanying drawings illustrate one complete example of thephysical embodiment of the invention, constructed according to the bestmode so far devised for the practical application of the principlesthereof, and in which:

FIGURE 1 is a view essentially in vertical section through the airheating and circulating unit of this invention;

FIGURE 2 is a horizontal cross sectional view through FIGURE 1 on theplanes of the line 2-2;

FIGURE 3 is a horizontal cross sectional view through FIGURE 1 on theplane of the line 33;

FIGURE 4 is a fragmentary detail sectional view through FIGURE 2 on theplane of the line 44;

FIGURE 5 is a top view of the unit with parts thereof broken away;

FIGURE 6 is a detail horizontal sectional view through FIGURE 1 on theplane of the line 66;

FIGURE 7 is a perspective view at a reduced scale of the complete unit;

FIGURE 8 is a vertical sectional view through a tobacco curing barn withthe air heating and circulating unit of this invention positionedtherein and coacting with the structure of the barn to effect thedesired circulation of air; and

FIGURE 9 is a plan view of the barn floor, or a horizontal sectionalview on the plane of the line 99 in FIGURE 8.

Referring now particularly to the accompanying drawings in which likenumerals indicate like parts throughout the several views, the numeral10 designates generally a conventional tobacco curing barn having afloor 11 which often is simply the ground upon which the barn iserected, and racks 12 from which the tobacco leaves are hung insuperimposed tiers, as is customary.

Also as is customary, the barn may be equipped with a controllableventilator 13 which is kept closed during the stem-killing portion ofthe curing cycle, and is open during the drying of the tobacco leaves topermit moisture laden air to escape from the barn.

Set directly upon the floor 11 and substantially centraily thereof, isan air heating and circulating unit 14. As distinguished from airheating and circulating units or furnaces heretofore available totobacco growers, such as those of the Mac-Cracken Patent No. 2,611,599,and the Taylor Patent No. 3,109,637, the unit 14 is entirelyself-contained and requires no ducts or spreaders to achieve the desireddistribution of heated air within the barn. Instead, it is designed toutilize and coact with the floor of the barn to eifect the neededdistribution of heated air throughout the barn interior, with thehottest gases and air flowing along the floor and radiating in all directions from the unit towards the perimeter of the floor. Beingself-contained, the unit 14 is also portable so that it may be placedwherever it produces the most effective and uniform circulation.

Since the hottest gases and air flow along the floor of the barn, thelowermost tiers of tobacco leaves can be hung much lower, without dangerof overheating and, as a result, the effective capacity of the barn isincreased.

The unit 14 comprises an outer casing 15 in the form of an invertedcup-shaped open bottomed sheet metal shell having a cylindrical sidewall 16 and a conical top wall 17. Located in the lower portion of thecasing or shell 15 is a fire pot 18, preferably formed of refractorymaterial and having a flat bottom wall 19 and an upright cylindricalside wall 20.

The fire pot is supported and held in spaced concentric relationship tothe side wall 16 of the outer shell or casing by being seated in a metalring 21, which in turn is supported in fixed relation to the casing byfour legs 22. These legs are welded to the ring 21 and to the casingside wall, and project down beyond the bottom edge 23 of the side wallto Space the same from the floor. The resulting annular opening betweenthe bottom edge 23 and the floor constitutes the outlet for the unitfrom which the heated air debouches to flow across the floor, as notedhereinbefore; and a hole 17' in the conical top wall of the casing orshell provides its inlet.

Suspended above the fire pot 18 in the upper portion of the casing 15,is a hood 24. This hood and the fire pot together define a combustionchamber CB, and coact with the walls of the casing to define an airpassage AP surrounding the combustion chamber and connecting the inletand outlet of the unit. The hood 24 has a cylindrical side wall or skirtprovided by a stainless steel ring 25, and a conical top wall 26 whichforms a flame shield across the top of the combustion chamber and thusis preferably molded or otherwise made of good heat insulating material,such as compacted ceramic fibers. The conical flame shield or top wall26 rests upon but is not connected to the stainless steel ring which hasan inturned flange 27 to provide a smooth flat surface for the flameshield to seat upon. Hence the flame shield is free to shift withrespect to the ring 25 as the differences in coeificients of expansionbetween them cause the flame shield to contract with increasedtemperature, while the stainless steel ring expands.

The periphery of the conical flame shield or top wall 26 is reinforcedand protected by an encircling metal band 28 of channel-shaped crosssection, and to maintain the desired tight fit of the band on the edgeof the flame shield despite the difference in their coeflicients ofexpansion and contraction, the band is formed in a plurality of sections28 that are drawn together by springs 29. Since the band embraces theedge of the flame shield, its lower flange is interposed between theshield and the flange 27 and thus protects the shield against scufiingas it moves with respect to the ring 25.

To hold the flame shield or conical top wall 26 concentric with thestainless steel ring 25 without interfering with their required freedomto shift relative to one another, lugs 30 are resiliently mounted on theshield and project down over the ring. For this purpose-as best seen inFIGURE 4-the springs 29 pass through holes in the lugs.

The hood 24 is supported from the side wall 16 of the casing inconcentrically spaced relation with it and with the side Wall 20 of thefire pot, by a plurality of webs or brackets 31 fixed to the stainlesssteel ring 25 and to the casing side wall.

At its top, the conical wall or flame shield 26 has a round hole 32 intowhich the lower end of a burner tube 33 fits. This tube houses a fuelburner nozzle 34 and has its upper endwhich is square in crosssectiondisposed in the hole 17 which provides the inlet to the airpassage AP, to receive some of the air delivered to the inlet by ablower, indicated generally by the numeral 35. The lower end of theburner tube 33 projects into the hole 32 and the tube is supportedtherein by a collar 36 welded or otherwise fixed to the tube and restingon the top wall 26 of the hood.

he burner nozzle 34 which may be of any conventional type, has anorifice tip 37 to which fuel under pressure is supplied by a fuel line38 when a solenoid actuated fuel valve 39 is open. As is customary,energization of the solenoid which opens the fuel valve is con trolledby a thermostat 42 having a sensing element 43 positioned to beresponsive to the temperature of the air entering the air passage.Ignition of the fuel issuing from the nozzle tip 37 is effected by aspark drawn across the tips of electrodes 44 which are supplied withhigh voltage from a transformer 45.

The blower 35 is of the conventional squirrel-cage type having a housing46 with guard-protected air inlet openings 47 in its opposite end walls48, and a downwardly facing outlet 49 which projects into the hole 17 inthe top of the casing or shell 15. Functionally, therefore, the actualair inlet of the unit is provided by the inlet openings 47 of theblower, since it is at those points where the air in the barn enters theunit.

An electric motor 50 suitably mounted on the blower housing 46 drivesthe bladed wheel 51 of the blower as well as the impeller, not shown, ofa fuel pump 52 which delivers fuel under pressure to the fuel valve 39,it being understood that the pump is connectible with a source of fuel,as by a fuel line 54. The hub 55 of the blower wheel may be fixeddirectly to the motor shaft, but the impeller of the fuel pump isconnected therewith through a flexible couple 56.

As will be readily apparent, the burner tube 33 cooperates with the hood24 and the fire pot 18 to complete the division of the interior of thecasing 15 into the combustion zone or chamber CB and the surrounding airpassage AP, so that by properly proportioning the air entering themouths of the burner tube and the surrounding air passage, the correctamount of air to achieve optimum combustion will be fed to thecombustion zone. One way of obtaining the desired proportioning of theincoming air is by using a burner tube of fixed cross sectional area andadjusting the size of the air inlet into the air passage by selectiveplacement of a blower housing cutoff plate 57. Obviously, once thatplacement has been determined, the position of the cutoff plate can befixed. In the structure illustrated, the edge 57' of the cutoff iscontiguous to the adjacent side of the burner tube.

When the unit is in operation, the combustible mixture of fuel and airissuing from the discharge end of the burner tube, burns in thecombustion chamber CB and the resulting hot combustion gases andproducts of combustion leave the combustion chamber and enter the airstream flowing downwardly through the surrounding air passage AP,through the annular opening 60 between the skirt or side wall 25 of thehood and the upper edge portion of the fire pot side wall 20. Since therate at which the gases leave the combustion zone or chamber has animportant bearing upon the completeness or quality of the combustion,the size of the opening 60 through which the gases leave may have to beempirically determined, but once that has been done, the correctdimensions will be known.

It has been discovered that combustion is also improved, especiallyduring the start-up period, by creating a low pressure zone at the pointof confluence of the hot gases emanating from the combustion zone, andthe air stream flowing through the surrounding air passage. This isaccomplished by constricting the air passage directly upstream from thepoint of confluence, and-for this purposea flange 61 extends into theair passage from the side wall 16 of the casing at a level slightlyabove the bottom edge of the skirt or side wall 25 of the hood.

Still another factor that has a bearing upon the quality of thecombustion taking place in the combustion zone, is the degree to whichthe combustion zone is insulated from the relatively colder air movingthrough the air passage.

It is for this reason that the flame shield provided by the conical topwall 26 of the hood is formed of good heat insulating material.

The flame shield also has the important function of keeping the upperwalls of the casing, and especially its conical top wall 17, frombecoming dangerously hot and creating a fire hazard. Experience hasdemonstrated that none of the outside walls of the unit become hotenough to ignite a tobacco leaf which might fall onto the unit; and toafford safety against fire resulting from any malfunctioning of theunitwhich might cause flaming gases to be discharged through itsoutlet--a flame detector 62, of any conventional type, is mounted on thehood with its sensing element in the opening 60. This detector is, ofcourse, connected into the control circuit of the burner to shut oil thefuel supply before a dangerous situation can develop.

Attention is directed to the fact that the fire pot is supported withits bottom slightly off the floor on which the unit sets. This is doneto pennit air to circulate under the fire pot and prevent overheatingand premature failure of its bottom wall 19 due to the flame impingingthereon; and to promote such air circulation under the fire pot, an airdeflector 63 embraces part of the lower portion of the fire pot andprojects into the air passage. More specifically, the deflector 63, asshown in FIGURE 3, extends around one quadrant of the fire potsupporting ring 21 to which the deflector is attached by spacers 64.

As a matter of convenience in manufacture, the casing may be made inthree sections-a lower cylindrical section which has its upper edgeturned in to provide the flange 61 and has the legs 22 welded to itslower end; an intermediate cylindrical section which fits onto the upperflanged end of the lower section; and an upper conical section which issuitably secured to the top edge of the intermediate section andprovides the top wall 17 of the casing. To facilitate moving the unitfrom place to place, handles 65 are fixed to the top of the casing.

The thermostat 42 and the transformer 45 are preferably mounted on theblower housing, with the thermostat housed in a cabinet-like enclosure66 which has a front wall through which the control knob 67 of thethermostat projects, and on which the transformer is mounted.

If the barn floor 11 is simply dirt, as it is very often, it ispreferable to set the unit on a pad 68 of any fireproof material, tokeep dirt from being blown around by the air issuing from the unitor, ifdesired, a small concrete platform may be provided for this purpose.

From the foregoing description taken with the accompanying drawings, itwill no doubt be apparent to those skilled in the tobacco curing art,that this invention provides an exceptionally convenient, practical andinexpensive air heating and circulating unit, that not only possessesall the attributes of a good tobacco curing furnace, butin addition-canbe used for many other purposes because of its ready portability and thefact that it is self-contained.

What is claimed as my invention is:

1. Means for curing and drying tobacco comprising the combination of:

(A) a barn having a floor and structure to support tiers of tobaccoleaves within the barn; and

(B) an air heating and circulating unit in the barn to heat the airtherein and coact with the floor of the barn to effect forcedcirculation of the heated air with the hottest air flowing along thebarn floor towards the perimeter thereof, so that the lowermost tiers oftobacco leaves may be placed relatively near the floor of the barnWithout danger of being heated excessively, said air heating andcirculating unit comprising:

(1) an inverted cup-shaped casing having top and side walls defining anair chamber, the top wall having an inlet opening for the chamber andthe side wall having a free lower edge,

(2) leg means on the unit to support the same in an upright positionwith the free edge of the side Wall of its vcasing spaced from the floorso that said free edge coacts with the floor to provide an annularlaterally opening outlet for the air chamber through which air leavesthe unit to flow across the floor.

(3) structure Within said casing defining a combustion chamber having atop wall spaced down from the top wall of the casing and side wall meansspaced in from the side wall of the casing and extending down from thetop wall of the combustion chamber to a level adjacent to that of thefree edge of the casing side wall so that the walls of the combustionchamber and the casing cooperate to form an air passage surrounding thecombustion chamber and extending from the inlet of the air chamber toits outlet, the side wall means of the combustion chamber having outletmeans therein through which hot combustion gases and products ofcombustion can flow from the combustion chamber to join with air movingthrough said passage and issuing from the annular outlet;

(4) a burner nozzle arranged to direct flame into the combustionchamber,

(5) a blower on the casing with its inlet in open communication with theinterior of the barn and its outlet discharging into the inlet of theair chamber, and

(6) air flow directing means in the upper portion of the casing todirect air entering the inlet of the air chamber to said air passage fordischarge therefrom through the outlet along with the combustion gasesand products of combustion that enter said passage from the combustionchamber.

2. An air heating and circulating unit comprising:

(A) a cup-shaped casing having end and side walls, the end wall havingan opening for the admission of air to be heated and the side wallhaving a free edge;

(8) a cup-shaped fire pot in the open end portion of the casing, saidfire pot having an end wall and a side wall terminating in a free edgewhich defines the mouth of the fire pot;

(C) bridging members connecting the fire pot with the side wall of thecasing, said bridging members being spaced from one another and holdingthe fire pot spaced from and substantially coaxial with the side wall ofthe casing with the end wall of the fire pot axially adjacent to thefree edge of the casing side wall, whereby the side walls of the casinand the fire pot coact to provide an axially extending annular airpassage of substantial length and where by the free edge of the casingside Wall and the adjacent outer surface of the fire pot coact to providan annular outlet for the unit leading from said annular air passageadjacent to the end wall of the fire pot;

(D) a flame shield in the casing between the mouth of the fire pot andthe end Wall of the casing, said flame shield being larger than themouth of the fire pot;

(E) means mounting the flame shield in the casing with its outer edgeportion spaced axially from and projecting laterally beyond the mouth ofthe fire pot and with its outer edge spaced from the side Wall of thecasing to coact therewith in providing an annular entrance to saidaxially extending annular air passage which entrance is substantiallysmaller in area than the annular air passage;

(F) a burner nozzle arranged to direct flame into the fire pot;

='(G) duct means surrounding the burner nozzle to supply combustion airto the fire pot; and

(H) air moving means on the casing to force air into the casing throughsaid opening in its end wall and against the flame shield for directionthereby to said annular entrance into the annular air passage past themouth of the fire pot, and through said annular air passage to theoutlet of the unit, the diflerence in area between the annular airpassage and the entrance thereto creating a low pressure zone closelyadjacent to the mouth of the fire pot, whereby hot combustion gases andproducts of combustion are educated from the fire pot to commingle withthe air flowing along the annular air passage to the output of thecasing.

3. The air heating and circulating unit of claim 2, wherein the burnernozzle and the duct means surrounding it opens through a hole in theflame shield, and the inlet end of said duct means is in line with theopening in the end wall of the casing,

wherein the air moving means is mounted on the end wall of the casingand comprises a blower having a rotatable air impeller dischargingthrough the opening in the casing end wall and into said air duct meansas well as into the interior of the casing,

so that the same blower provides air for combustion and circulates theair to be heated through the unit,

wherein the burner nozzle is supplied with fuel under pressure by a fuelpump, and wherein a single motor drives both the fuel pump and theimpeller of the blower.

4. The air heating and circulating unit of claim 2, furthercharacterized by:

leg means On the unit to support the same on a floor, with its axisvertical and said end wall of the fire pot contiguous to the floor,

so that the annular outlet of the unit is directly adjacent to thefloor.

5. The air heating and circulating unit of claim 4, wherein said flameshield mounting means comprises a supporting rin fixed to the side wallof the casing by spaced brackets,

the peripheral portion of the flame shield resting upon said supportingring and being free to move lat rally relative thereto to compensate fordifierences in coefficients of expansion and contraction therebetween.

6. The air heating and circulating unit of claim 5, wherein the flameshield is formed of good heat insulating material,

and further characterized by a metal reinforcing band on the peripheryof the flame shield,

said reinforcing band having a portion thereof interposed between theunderside of the peripheral portion of the flame shield and thesupporting ring.

7. The air heating and circulating units of claim 6, wherein the flameshield is formed of non-metallic heat insulating material,

and wherein said metal reinforcing band comprises a plurality ofsections, each U-shaped in cross section,

and spring means yieldingly drawing said sections together to at alltimes reinforcingly confine the peripheral portion of the flame shield.

8. The air heating and circulating unit of cla m 7, furthercharacterized by:

a flat flange at the upper edge of the supporting ring upon which thereinforcing band rests.

9. The air heating and circulating unit of claim 4, wherein said legmeans are part of the bridging members and project below the free edgeof the casing side wall,

and wherein the connection of the bridging members with the fire potcomprises a ring fixed to the bridging members and in which the fire potis supportingly received.

10. An air heating and circulating unit comprising:

(A) a cup-shaped casing having end and side walls, the end wall havingan opening for the admission of! air to be heated and the side wallhaving a free e ge;

(B) structure defining a combustion chamber within said casing, saidstructure providing the combustion chamber with a side wall and an endwall remote from the end wall of the casing;

(C) bridging members rigidly connecting the casing side wall with thestructure that defines the combustion chamber, said bridging membersbeing spaced from one another and holding the combustionchamber-defining structure spaced inwardly of the casing side wall withsaid end wall of the combustion chamber axially adjacent to the freeedge of the casing side wall, whereby an annular outlet is provided forthe unit adjacent to said end wall of the combustion chamber;

(D) a burner nozzle arranged to project flame into the combustionchamber;

(E) duct means surrounding the burner nozzle to supply combustion air tothe combustion chamber;

(F) means providing communication from the interior of the combustionchamber to said annular outlet, through which hot combustion gases andproducts of combustion flow from the combustion chamber to said outlet;

(G) air moving means on the casing to force air into the casing throughthe opening in its end wall;

(H) air directing means by which air entering the casing is caused toflow between the side walls of the casing and the combustion chamber andto issue from said annular outlet along with the hot combustion gasesand products of combustion; and

(1) legs fixed to the casing side wall and projecting axially beyond itsfree edge and beyond said end wall of the combustion chamber to supportthe unit upon a floor with said end wall of the combustion chambercontiguous to the floor and the free edge of the casin side wall spacedabove the floor.

References Cited UNITED STATES PATENTS 1,863,391 6/1932 Bluemel.2,611,599 9/1952 MacCracken. {2,637,375 5/1953 Tapp et al. 2,896,933 7/1959 Barnes. 3,109,637 11/1963 Taylor.

FREDERICK L. MATTESON, 1a., Primary Examiner.

E. G. FAVORS, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,388,900 June 18, 1968 John S. Taylor It is certified that errorappears in the above identified patent and that said Letters Patent areherebycorrected as shown below:

Column 1, line 66, "bot" should read hot Column 7, line 11, "educated"should read educted line 12, "output" should read outlet Signed andsealed this 18th day of November 1969.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer

